Solar Charge Controller: MPPT or PWM?

Do you need a solar charge controller for your photovoltaic system but you don't know which one to choose? The market offers different types of solar charge controllers at different prices. But what is the right one for you? It is therefore very important to know their characteristics and how they work in order to make a purchase safe and durable. Mppt Solar has selected for this market two of the best charge controllers for solar panels and has created this information page to help you in choosing the right charge controller for your photovoltaic system based on the type of panels and battery want to install. If during the planning of your PV system to the island you have decided to choose certain panels instead of others is good to know that this choice may suggest a regulator rather than another. Our charge controllers are of two technologies: mppt and pwm.

Where to use a mppt solar controller and where to use a pwm one?

As we said, the choice of technology of the charge depends on the type of panels that have or want to install both the battery bank. The controller pwm normally costs less than an MPPT controller, but the controller mppt is able to take full advantage of a solar panel with voltage higher than the batteries bank one and therefore enables the production of more energy compared to a regulator pwm. If the voltage of the panel is slightly greater than that of the battery (typical case of a panel to 12V and 12V battery 30 cells), the controller pwm is recommended because it has a daily yield in this case similar all'mppt. Below so we made a very simple table where you will find the technology of the charge controller to use based on:

1) Number of cells that make up your panels

2) Voltage of the battery bank that you want to charge

Panels + Batteries

Type of Controller

36 cells Panels + 12V Batteries

MPPT

48 cells Panels + 12V/24V Batteries

MPPT

54 cells Panels + 12V/24V Batteries

MPPT

72 cells Panels + 12V/24V Batteries

MPPT

144 cells Panels + 48V Batteries

MPPT

30 cells Panels + 12V Batteries

PWM

60 cells Panels + 24V Batteries

PWM

120 cells Panels + 48V Batteries

PWM

How to understand the voltages of the panels according to their cells?

Panel Cells

Rated Voltage

Open Circuit Voltage

30 cells

12V

18V

36 cells

12V

21V

48 cells

18V

30V

54 cells

18V

33V

60 cells

24V

36V

72 cells

24V

42V

120 cells

48V

72V

144 cells

48V

84V

What is the behavior of the two solar charge controllers technologies?

And now we see two photos we took to show the behavior of the current in the pwm charge controller PR3030 and mppt charge controller Solarix. As we used a panel solar panel 100W monocrystalline silicon. The angle of the panel was not exactly perpendicular to the sun's rays needed for a "photographic". The battery is a 12V Lead-acid Fiamm battery.

1) Pwm solar charge controller PR3030

As can be seen from the picture, leaving the panel we have a current of 1.60 A, which is used almost entirely by the controller pwm (1.57 A) to charge the 12V battery. The solar charge controller PR3030 can withstand currents of up to 30A and also presents the display function of the percentage of battery charge. In this case, informs us that the battery is charged to 76%.

2) Mppt solar charge controller Solarix

Unlike the regulator pwm which considers only the current to the end of charging, the regulator mppt Solarix considers all the power of the photovoltaic panel (then voltage and current). In fact the difference between the voltage delivered by the panel (example 36V) and the necessary voltage to the battery at that moment (example 14V) is not lost but is transformed by the current regulator mppt useful to the process of charging. From the picture it is seen that the output current from the panel is of 1.68 A, but the current that goes to the battery is even of 2.07 A. With the mppt solar charge controller Solarix use all the power of the panel!